Emergency Trench Shoring and Rescue: A Simplified Method for Calculating Lateral Earth Pressures

Table 1

T-L method resistance calculations as a function of the lateral extent of the observed failure.

Furthest lateral extent of observed failure, L		T-L method resistance calculations
		RT-L (kips)						RT-L (kN)
		Trench depth						Trench depth
ft	m	4 ft	8 ft	12 ft	16 ft	20 ft		1.2 m	2.4 m	3.7 m	4.9 m	6.1 m
1.5	0.5	1.7	3.3	5.0	6.6	8.3	1.7	7.5	15.0	22.5	30.0	37.5	7.5
2.0	0.6	2.2	4.4	6.6	8.8	11.0	2.2	10.0	20.0	30.0	40.0	50.0	10.0
2.5	0.8	2.8	5.5	8.3	11.0	13.8	2.8	12.5	25.0	37.5	50.0	62.5	12.5
3.0	0.9	3.3	6.6	9.9	13.2	16.5	3.3	15.0	30.0	45.0	60.0	75.0	15.0
3.5	1.1	—	7.7	11.6	15.4	19.3	3.9	—	35.0	52.5	70.0	87.5	17.5
4.0	1.2	—	8.8	13.2	17.6	22.0	4.4	—	40.0	60.0	80.0	100.0	20.0
4.5	1.4	—	9.9	14.9	19.8	24.8	5.0	—	45.0	67.5	90.0	112.5	22.5
5.0	1.5	—	11.0	16.5	22.0	27.5	5.5	—	50.0	75.0	100.0	125.0	25.0
5.5	1.7	—	12.1	18.2	24.2	30.3	6.1	—	55.0	82.5	110.0	137.5	27.5
6.0	1.8	—	—	19.8	26.4	33.0	6.6	—	—	90.0	120.0	150.0	30.0
6.5	2.0	—	—	21.5	28.6	35.8	7.2	—	—	97.5	130.0	162.5	32.5
7.0	2.1	—	—	23.1	30.8	38.5	7.7	—	—	105.0	140.0	175.0	35.0
7.5	2.3	—	—	24.8	33.0	41.3	8.3	—	—	112.5	150.0	187.5	37.5
8.0	2.4	—	—	26.4	35.2	44.0	8.8	—	—	120.0	160.0	199.9	40.0
8.5	2.6	—	—	28.1	37.4	46.8	9.4	—	—	127.5	170.0	212.4	42.5
9.0	2.7	—	—	—	39.6	49.5	9.9	—	—	—	180.0	224.9	45.0
9.5	2.9	—	—	—	41.8	52.3	10.5	—	—	—	190.0	237.4	47.5
10.0	3.0	—	—	—	44.0	55.0	11.0	—	—	—	199.9	249.9	50.0
10.5	3.2	—	—	—	46.2	57.8	11.6	—	—	—	209.9	262.4	52.5
11.0	3.4	—	—	—	48.4	60.5	12.1	—	—	—	219.9	274.9	55.0
11.5	3.5	—	—	—	—	63.3	12.7	—	—	—	—	287.4	57.5
12.0	3.7	—	—	—	—	66.0	13.2	—	—	—	—	299.9	60.0
12.5	3.8	—	—	—	—	68.8	13.8	—	—	—	—	312.4	62.5
13.0	4.0	—	—	—	—	71.5	14.3	—	—	—	—	324.9	65.0
13.5	4.1	—	—	—	—	74.3	14.9	—	—	—	—	337.4	67.5
14.0	4.3	—	—	—	—	77.0	15.4	—	—	—	—	349.9	70.0

Note: the maximum extent of L is determined based on the Coulomb failure wedge of a soil with a friction angle of 20°.